Engine starter



Dec. 5, 1939- J. w. FITZ GERALD 84 ENGINE STARTER Filed Jan. 13, 1938 Patented Dec. 5, 1939 PATENT oFFl'ca amass enema s'ma'rm John W. rm Gerald. Milwaukee, Wis, assignor to Briggs & Stratton Corporation, Milwaukee,

, a corporation of Delaware Application January 13 1938, SerialNo. 184,809

13 Claims. (01. 'i4'l) This invention relates to improvements in engine starters ofv the type forming the subject matter of Patent No. 2,098,866 issued to John W. Fitz Gerald on November 9, 1937, and refers particularly to the provision of means for holding the pinion in its retracted position to guard against the possibility of having it move-into engagement with the ring gear when the engine is running.

Heretofore, the means provided for this purpose invariably consisted of some form of spring pressed friction element engaging the pinion or a part thereof when in its retracted position to releasably hold it there. While these past expedients have; for the most part accomplished tion to provide magnetic means for releasably holding the pinion in its retracted position.

It is also an object of this invention toprovide a magnetic anti-creep device, for the purpose set forth, which is so designed that it is entirely embedded in the parts of the starter and in nowise necessitates complications in design or construction.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter-described, and more particularly delined by the appended claims, it being understood that such changes in the precise embodiment of v the hereindisclosed invention may be made as come within the scope of the claims.

The accompanyingdrawing illustrates several complete examples of the physical embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a longitudinal sectional view through an engine starter embodying one form of this invention;

Figure 2 is a cross sectional view taken through Figure l on the plane of the line 2-2;

Figure 3 is a detailed sectional view showing a starter construction similar to that of Figure 1, but with a slightly modified manner of mounting the magnet;

Figurei is aviewsimilartoFigure 1 illustrating a different type of starter; and. showing another manner of mounting the magnet; Figure 5 is a cross sectional view takenthrough Figure 4 on the plane of the line H; and v Figure 6 is a perspective view of the magnet employed in the construction shown in Figures 4 and 5. a 1

Referring now particularly to the accompanying drawing in which like numerals designate like parts, throughout the several views, the numeral 6 designates a shaft driven by an electric motor 8 or any other suitable prime mover. Mounted to move longitudinally along the shaft I and to rotate therewith is a pinion I. This pinion is' adapted to be propelled forwardly from its retracted position shown in Figure 1 into mesh with a i gear 8 which, as is customary, is carried by the flywheel of the engine with which the starter is associated.

The pinion I has an internally threaded extension 9 threaded on a sleeve Ill whichforms part of an actuating member slidable directly on the shaft 5. An annular flange ii on the actuating member is held in frictional engagement with one side of a rubber collar l2 encircling the outer end of the shaft, the opposite face of which is frictionally engaged with a flange l3 flxed to the shaft. An outer shell or sleeve .ll encircling the rubber collar and having inturned flanges mgaging over the edges of the flanges II and It holds the rubber collar under sufllcient compression to provide a frictional driving connection from the shaft carried collar It to the actuating member.

As will be readily apparent, upon rotation of the shaft 5, the inertia ofthepinion and its part I holds the pinion against rotation so that the threaded connection between the pinion and theactuating member propels the pinion forwardly into mesh with the ring gear. The elasticity of the rubber collar cushions the driving connection between the shaft and thepinion to compensate for possible misalignment of the pinion and ring gear teeth during meshing of the pinion with the ring gear and also cushions the application of the engine load to the starting moto as described in the aforesaid patent.

when the engine starts to operate under its;

own power, it drives the pinion at a speed greater than that of the motor shaft and consequently the actuating member, so that the threaded connection quickly retracts the pinion. Retraction of the pinion is limited by the engagement of retracted position, it be held against the rebound ing back into engagement with the ring gear or against creeping forwardly into contact with the ring gear. This is the function of the anti-creep device of this invention In one of its embodiments as illustrated in Figures 1 and 2 it consists of two permanent magnet bars i5 mounted diametrically opposite in the inner end portion of the internally threaded extension 9 on the pinion. I

These permanent magnet bars are threaded in the bottoms of holes l6, large enough to provide magnetic clearance. The magnet bars exert a strong magnetic attraction for the adjacent face of the flange H, which, of course, is made of magnetic metal. With this construction, the part in which the permanent magnet bars are mounted, is of steel or other magnetic metal.

The strength of the magnets is suflicient hold the pinion in its retracted position against a tendency to rebound or creep forwardly, but is insufficient to offset the inertia of the pinion during the initial starting operation.

If desired, the permanent magnet bars may be inserted in the outer 'end of the pinion extension by being embedded in'a non-magnetic material I! as shown in Figure 3.

Another modified embodiment of the invention as illustrated in Figures 4, 5 and 6 consists in the provision of a substantially U-shaped permanent magnet l8 embedded 'directlyin the inner end of the actuating member l9 which, in this instance, is formed of a non-magneticmaterial and may bea die casting. Here, the pinion 5' has an "externally threaded sleeve 20 and slides directly on the shaft 5. The difference in diam- 'eter between the pinion and the sleeve 20 provides a shoulder or'fiat face 2| at the rear or outer end of thepinion. This shoulder or flat face engages from creeping or rebounding forwardly into engagement with the ring gear.

What I claim as my invention is: 1. In an engine starter, the combination with a power driven shaft, a pinion slidable along the shaft into mesh with a ring gear and means to propel the pinion along the shaft into mesh with the ring gear and retract the same out of mesh with the ringgear upon starting of the engine: of magnetic means for attracting and releasably holding the pinion in its retracted position.

2. An engine starter, comprising the combination of: a power driven shaft; a pinion movable longitudinally along the shaft and rotatable with the shaft; and cooperating parts carried by the shaft and the pinion and having a threaded connection therebetween for effecting motion of the pinion from and to a retracted position; characterized by the provision of means for releasably holding the pinion inits retracted position com-' prising a permanent magnet carried by one of said parts and so mounted with respect to the other part as to exert a magnetic attraction therefor. w

3. In an engine starter of the character described: a power driven shaft; a pinion movable longitudinally alongthe shaft and rotarily therewith; cooperating elements carried by the shaft and the pinion for effecting motion of the pinion from and to a retracted position; anda magnet carried by one of said cooperating elements and mountedtoexert a magnetic attraction on the otherof said elements for releasably holding the pinion in its retracted position.

. 4. In an engine starter of the character described: a power driven shaft; a pinion movable longitudinally along the shaft and rotarily therewith; means for; propelling the pinion along the I shaft from and to a retracted position including tion; and a permanent magnet'carried byfone', of said elements with'a portion thereof. exposed at its said surface to be engaged wit'h'said sup, face of the other element 'for releasably the pinion in its retracted position. v

5. In "an engine starter of the character described: a power-driven'shaft; a pinion movable longitudinally along the shaft and rotarily therewith; means for propelling the pinion along the o d ng shaft from and to a retracted position including cooperating elements, one of .whichlis'fixed with respect to the pinion, means connecting the other of said elements with the shaft so as to be driven thereby, and a threaded connection between said elements, said elements having surfaces adapted tion; and a permanent magnet entirely within the confines of one of said elements having a pole so located with respectto the'said surface of said elementas to'have"magnetic influence upon the'said-surface of the other element for releasably holding the pinion in its retracted position. 6. In an engine starter of 'the' character described: a power driven shaft; a pinion movable longitudinallyalong'the shaft" and rotarily theree with; means for propellingthe pinion along the shaft from and'to a retracted position including cooperating elements, one of which is fixed with respect to the pinion, means connecting the other of said elements with the shaftso as to be driven thereby, and'a threaded connection between said elements, said elements havingsurfaces adapted to abut when the pinion is in its retracted position; and a permanent magnet embedded in the body of one of said elements with one pole thereof exposed at its'said surface to be engageable with said surface of the other element for releasably holding the pinion in its retracted position.

7.In an engine starter ofrthe character described: a power driven shaft; a pinion movable longitudinally along the-shaft from and to a retracted position; cooperating elements, one of which is fixed with respect to the pinion, means connecting the other of said elements with the U shaftso as to be driven thereby, and a threaded connection between said elements for propelling the pinion longitudinally alongthe shaft from andto its retracted position, one of said elements being of. nonmagneticmaterial and theother beportion thereof disposed to exert magnetic influence upon the magnetic element when the pinion is in its retracted position for releasably holding the pinion in its retracted. position.

8. In an engine starter of'the character described: a power driven shaft; a pinion movable longitudinally along the shaft from and to a retracted position; cooperating elements, one of which is fixed with respect .to the pinion, means connecting the other of said elements with the shaft so as to be driven thereby, and a threaded connection between said elements for propelling the pinion longitudinally along the shaft from and to its retracted position, one of said elements being of nonmagnetic material and the other being of magnetic material; and a permanent magnet embedded in the body of the nonmagnetic element with a portion thereof located to exert magnetic influence upon the magnetic element when the pinion is retracted for releasably holding the pinion in its retracted position.

9. In an engine starter of the character described: a pinion having a threaded part; a power driven member having a part threaded to said pinion part and operable to propel the pinion longitudinally from and to a retracted position; one of said parts being formed of magnetic metal; and a permanent magnet'carried by the other part and having a pole arranged to exertmagnetic influence upon said magnetic part for releasably holding the pinion in its retracted position.

10. In an engine starter of the character described: a pinion having a threaded part: power driven instrumentalities for propelling the pinionv longitudinally from a retracted position to a driving positionand for imparting driving force thereto, said instrumentalities including a part thread ed to said pinion carried part; one of said parts being formed of magnetic metal and the other being formed of nonmagnetic metal, and said parts having surfaces adapted to engage when the pinion is retracted; and a permanent magnet carried by the nonmagnetic part with a pole adjacent to its said surface to exert magnetic influence upon the said surface of the magnetic part for releasably holding the pinion in its retracted position.

11. In an engine starter of thecharacter described: a power driven shaft; a pinion movable longitudinally along the shaft from and to a retracted position; an actuating member having a threaded connection with the pinion; a yielding driving connection between the actuating member. and the-shaft, said pinion and actuating memher having portions located in juxtaposition when w 12. In an engine starter of the character described: a power driven shaft; an actuating member mounted on the shaft and drivingly connected thereto; a pinion movable longitudinally along the shaft from and to a retracted position: a threaded connection between the pinion and the actuating member; said actuating member and the pinion having portions disposed in juxtaposition when the pinion is in retracted position, said portion of the actuating member being of-magnetic metal; and a permanent magnet carried by said portion of thepinion with a pole arranged to exert magnetic attraction on said magnetic portion for releasably holding the pinion in its retracted position.

13. In an engine starter of the character described: a power driven shaft; a pinion slidable longitudinally along the shaft from and to a retracted position; a threaded extension on the pinion smaller in diameter than the pinion so as to leave a shoulder at the back of the pinion; said pinion being formed of magnetic metal; an actuating member drivingly connected with the shaft and threaded on said threaded extension of the pinion so that upon rotation of the shaft the pinion is propelled away from its retracted JOHN w. FITZ GERALD. 

